1. Field of the Invention
In one aspect this invention relates to eye protection for combat personnel. In yet a further aspect, this invention relates to methods of absorbing light beams.
2. Prior Art
Laser technology has become an increasingly important part of modern technological warfare. Lasers are used in aiming devices, range finders, and as countermeasures to defeat various optical aiming and ranging devices.
As part of the development of laser technology, tuneable dye lasers are being developed which operate by pumping from other lasers or flash lamps. Such lasers provide high energy pulses and can be made in large variety of different wave lengths. The TI-Sapphire lasers now being developed can also provide high repetitions of tuneable energy. This means the exact wave length used by an opponent can not be known in advance requiring that any acceptable protection device be useful over a broad spectrum.
Thus, battlefield personnel are in danger of being exposed to laser radiation of an unknown frequency either casually or intentionally. With the power densities available from today's laser technology, serious damage will be done to unprotected eyes and also the optical devices used on combat vehicles. The radiation comes in discrete bursts of ebergy ranging from a few microjoules up to several joules in intensity and for periods of time from a few nanoseconds to a few microseconds.
To prevent eye damage, any light absorption device must react quickly, on the order of less than 10 picoseconds and absorb light in the range of 400 to 700 nm. Because of the limited time to react, the device must operate passively. A further constraint is the device must transmit light of normal intensity so the user can function in normal light conditions while the bursts of high intensity are prevented from reaching the users eye. This implies that the absorption material operates in a nonlinear manner or initiates protection at some predetermined minimum beam power.
Indirect viewing means which protect a viewer have been developed. One such class of viewers includes a system where the incoming light signal is amplified until all signal are equal in strength and then the modified light beam is attenuated to a safe level. These devices are large and bulky, and also require an external power source making them unsuitable for battlefield application. Particularly with respect to viewers carried by personnel.
Attempts have been made to develop goggles which are suitable for attenuating incoming laser beams during the last several years. The attenuation must be to a power level of about 1 .mu.j which represents an attenuation factor of at least 10,000 since the available lasers can deliver up to several joules of power in the beam with little beam divergence. Partial solutions for beams at a preselected wave length have been achieved; however, there presently exist no protective systems for personnel and equipment which are passive, can react to a broad spectrum of high intensity beams, and simultaneously allow the user to function under normal light conditions.